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  Computer system para-virtualization using a hypervisor that is implemented in a partition of the host systemUSPTO Application #: 20070028244Title: Computer system para-virtualization using a hypervisor that is implemented in a partition of the host system Abstract: A virtualization infrastructure that allows multiple guest partitions to run within a host hardware partition. The host system is divided into distinct logical or virtual partitions and special infrastructure partitions are implemented to control resource management and to control physical I/O device drivers that are, in turn, used by operating systems in other distinct logical or virtual guest partitions. Host hardware resource management runs as a tracking application in a resource management “ultravisor” partition, while host resource management decisions are performed in a higher level command partition based on policies maintained in a separate operations partition. The conventional hypervisor is reduced to a context switching and containment element (monitor) for the respective partitions, while the system resource management functionality is implemented in the ultravisor partition. The ultravisor partition maintains the master in-memory database of the hardware resource allocations and serves a command channel to accept transactional requests for assignment of resources to partitions. It also provides individual read-only views of individual partitions to the associated partition monitors. Host hardware I/O management is implemented in special redundant I/O partitions. Operating systems in other logical or virtual partitions communicate with the I/O partitions via memory channels established by the ultravisor partition. The guest operating systems in the respective logical or virtual partitions are modified to access monitors that implement a system call interface through which the ultravisor, I/O, and any other special infrastructure partitions may initiate communications with each other and with the respective guest partitions. The guest operating systems are modified so that they do not attempt to use the “broken” instructions in the x86 system that complete virtualization systems must resolve by inserting traps. (end of abstract)
Agent: Unisys Corporation - Blue Bell, PA, US Inventors: John A. Landis, Terrence V. Powderly, Rajagopalan Subrahmanian, Aravindh Puthivaparambil, James R. Hunter USPTO Applicaton #: 20070028244 - Class: 718108000 (USPTO) Related Patent Categories: Electrical Computers And Digital Processing Systems: Virtual Machine Task Or Process Management Or Task Management/control, Task Management Or Control, Process Scheduling, Multitasking, Time Sharing, Context Switching The Patent Description & Claims data below is from USPTO Patent Application 20070028244. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The invention relates to computer system para-virtualization using a hypervisor that is implemented in a distinct logical or virtual partition of the host system so as to manage multiple operating systems running in other distinct logical or virtual partitions of the host system. The hypervisor implements a partition policy and resource services that provide for more or less automatic operation of the virtual partitions in a relatively failsafe manner. BACKGROUND OF THE INVENTION [0002] Computer system virtualization allows multiple operating systems and processes to share the hardware resources of a host computer. Ideally, the system virtualization provides resource isolation so that each operating system does not realize that it is sharing resources with another operating system and does not adversely affect the execution of the other operating system. Such system virtualization enables applications including server consolidation, co-located hosting facilities, distributed web services, applications mobility, secure computing platforms, and other applications that provide for efficient use of underlying hardware resources. [0003] Virtual machine monitors (VMMs) have been used since the early 1970s to provide a software application that virtualizes the underlying hardware so that applications running on the VMMs are exposed to the same hardware functionality provided by the underlying machine without actually "touching" the underling hardware. For example, the IBM/370 mainframe computer provided multiple virtual hardware instances that emulated the operation of the underlying hardware and provided context switches amongst the virtual hardware instances. However, as IA-32, or x86, architectures became more prevalent, it became desirable to develop VMMs that would operate on such platforms. Unfortunately, unlike the IBM/370 mainframe systems, the IA-32 architecture was not designed for full virtualization as certain supervisor instructions had to be handled by the VMM for correct virtualization but could not be handled appropriately because use of these supervisor instructions did not cause a trap to be generated that could be handled using appropriate interrupt handling techniques. [0004] In recent years, VMWare and Connectix have developed relatively sophisticated virtualization systems that address these problems with IA-32 architecture by dynamically rewriting portions of the hosted machine's code to insert traps wherever VMM intervention might be required and to use binary translation to resolve the traps. This translation is applied to the entire guest operating system kernel since all non-trapping privileged instructions have to be caught and resolved. Such an approach is described, for example, by Bugnion et al. in an article entitled "Disco: Running Commodity Operating Systems on Scalable Multiprocessors," Proceedings of the 16.sup.th Symposium on Operating Systems Principles (SOSP), Saint-Malo, France, October 1997. [0005] The complete virtualization approach taken by VMWare and Connectix has significant processing costs. For example, the VMWare ESX Server implements shadow tables to maintain consistency with virtual page tables by trapping every update attempt, which has a high processing cost for update intensive operations such as creating a new application process. Moreover, though the VMWare systems use pooled I/O and allow reservation of PCI cards to a partition, such systems do not create I/O partitions for the purpose of hoisting shared I/O from the hypervisor for reliability and for improved performance. [0006] The drawbacks of complete virtualization may be avoided by providing a VMM that virtualizes most, but not all, of the underlying hardware operations. This approach has been referred to by Whitaker et al. at the University of Washington as "para-virtualization." Unlike complete virtualization, the para-virtualization approach requires modifications to the guest operating systems to be hosted. However, as will be appreciated from the detailed description below, para-virtualization does not require changes to the application binary interface (ABI) so that no modifications at all are required to the guest applications. Whitaker et al. have developed such a "para-virtualization" system as a scalable isolation kernel referred to as Denali. Denali has been designed to support thousands of virtual machines running network services by assuming that a large majority of the virtual machines are small-scale, unpopular network services. Denali does not fully support x86 segmentation, even though x86 segmentation is used in the ABIs of NetBSD, Linux, and Windows XP. Moreover, each virtual machine in the Denali system hosts a single-user, single-application unprotected operating system, as opposed to hosting a real, secure operating system that may, in turn, execute thousands of unmodified user-level application processes. Also, in the Denali architecture the VMM performs all paging to and from disk for all operating systems, thereby adversely affecting performance isolation for each hosted "operating system." Finally, in the Denali architecture, the virtual machines have no knowledge of hardware addresses so that no virtual machine may access the resources of another virtual machine. As a result, Denali does not permit the virtual machines to directly access physical resources. [0007] The complete virtualization systems of VMWare and Connectix, and the Denali architecture of Whitaker et al. also have another common, and significant, limitation. Since each system loads a VMM directly on the underlying hardware and all guest operating systems run "on top of" the VMM, the VMM becomes a single point of failure for all of the guest operating systems. Thus, when implemented to consolidate servers, for example, the failure of the VMM could cause failure of all of the guest operating systems hosted on that VMM. It is desired to provide a virtualization system in which guest operating systems may coexist on the same node without mandating a specific application binary interface to the underlying hardware, and without providing a single point of failure for the node. Moreover, it is desired to provide a virtualization system with failover protection so that failure of the virtualization elements and/or the underlying hardware does not bring down the entire node. It is further desired to provide improved system flexibility whereby the system is scalable and a system user may specify desired systems resources that the virtualization system may allocate efficiently over all available resources in a data center. The present invention addresses these limitations in the current state of the art. SUMMARY OF THE INVENTION [0008] The present invention addresses the above-mentioned limitations in the art by providing virtualization infrastructure that allows multiple guest partitions to run within a host hardware partition. The host system is divided into distinct logical or virtual partitions and special infrastructure partitions are implemented to control resource management and to control physical I/O device drivers that are, in turn, used by operating systems in other distinct logical or virtual guest partitions. Host hardware resource management runs as a tracking application in a resource management "ultravisor" partition while host resource management decisions are performed in a higher level "command" partition based on policies maintained in an "operations" partition. This distributed resource management approach provides for recovery of each aspect of policy management independently in the event of a system failure. Also, since the system resource management functionality is implemented in the ultravisor partition, the roles of the conventional hypervisor and containment element (monitor) for the respective partitions are reduced in complexity and scope. [0009] In an exemplary embodiment, an ultravisor partition maintains the master in-memory database of the hardware resource allocations. This low level resource manager serves a command channel to accept transactional requests for assignment of resources to partitions. It also provides individual read-only views of individual partitions to the associated partition monitors. Similarly, host hardware I/O management is implemented in special redundant I/O partitions. Operating systems in other logical or virtual partitions communicate with the I/O partitions via memory channels established by the ultravisor partition. [0010] In accordance with the invention, the guest operating systems in the respective logical or virtual partitions are modified to access monitors that implement a system call interface through which the ultravisor, I/O, and any other special infrastructure partitions may initiate communications with each other and with the respective guest partitions. In addition, the guest operating systems are modified so that they do not attempt to use the "broken" instructions in the x86 system that complete virtualization systems must resolve by inserting traps. This requires modification of a relatively few lines of operating system code while significantly increasing system security by removing many opportunities for hacking into the kernel via the "broken" instructions. [0011] In a preferred embodiment, a scalable partition memory mapping system is implemented in the ultravisor partition so that the virtualized system is scalable to a virtually unlimited number of pages. A log (2.sup.10) based allocation allows the virtual partition memory sizes to grow over multiple generations without increasing the overhead of managing the memory allocations. Each page of memory is assigned to one partition descriptor in the page hierarchy and is managed by the ultravisor partition. [0012] In the preferred embodiment, the I/O server partitions map physical host hardware to I/O channel server endpoints, where the I/O channel servers are responsible for sharing the I/O hardware resources. In an internal I/O configuration, this mapping is done in software by multiplexing requests from channels of multiple partitions through shared common I/O hardware. Partition relative physical addresses are obtained by virtual channel drivers from the system call interface implemented by the monitors and pass through the communication channels implemented by shared memory controlled by the ultravisor partition. The messages are queued by the client partition and de-queued by the assigned I/O server partition. The requested I/O server partition then converts the partition relative physical addresses to physical hardware addresses with the aid of the I/O partition monitor, and exchanges data with hardware I/O adaptors. The I/O partition monitor also may invoke the services of the partition (lead) monitor of the ultravisor partition and/or the guest partition's monitor, as needed. Command request completion/failure status is queued by the server partition and de-queued by the client partition. On the other hand, in an external I/O configuration, setup information is passed via the communication channels to intelligent I/O hardware that allows guest partitions to perform a signification portion of the I/O directly, with potentially zero context switches, by using a "user mode I/O" or direct memory access (DMA) approach. [0013] The ultravisor partition design of the invention further permits virtualization systems operating on respective hosts hardware partitions (different hardware resources) to communicate with each other via the special infrastructure partitions so that system resources may be further allocated and shared across multiple host nodes. Thus, the virtualization design of the invention allows for the development of virtual data centers in which users may specify their hardware/software resource requirements and the virtual data center may allocate and manage the requested hardware/software resources across multiple host hardware partitions in an optimally efficient manner. Moreover, a small number of operations partitions may be used to manage a large number of host nodes through the associated partition resource services in the command partition of each node and may do so in a failover manner whereby failure of one operations partition or resource causes an automatic context switch to another functioning partition until the cause of the failure may be identified and corrected. Similarly, while each command partition system on each node may automatically reallocate resources to the resource database lists of different ultravisor resources on the same multi-processor node in the event of the failure of one or more processors of that node, the controlling operations partitions in a virtual data center implementation may further automatically reallocate resources across multiple nodes in the event of a node failure. [0014] Those skilled in the art will appreciate that the virtualization design of the invention minimizes the impact of hardware or software failure anywhere in the system while also allowing for improved performance by permitting the hardware to be "touched" in certain circumstances. These and other performance aspects of the system of the invention will be appreciated by those skilled in the art from the following detailed description of the invention. BRIEF DESCRIPTION OF THE DRAWINGS [0015] A para-virtualization system in accordance with the invention is further described below with reference to the accompanying drawings, in which: [0016] FIG. 1 illustrates the system infrastructure partitions on the left and user guest partitions on the right in an exemplary embodiment of a host system partitioned using the ultravisor para-virtualization system of the invention. [0017] FIG. 2 illustrates the partitioned host of FIG. 1 and the associated virtual partition monitors of each virtual partition. [0018] FIG. 3 illustrates memory mapped communication channels amongst the ultravisor partition, the command partition, the operations partition, the I/O partitions, and the guest partitions. [0019] FIG. 4 illustrates the memory allocation of system and user virtual partitions, virtual partition descriptors in the ultravisor partition, resource agents in the command partition, and policy agents in the command partition and operations partition. [0020] FIG. 5 illustrates processor sharing using overlapped processor throttling. Continue reading... Full patent description for Computer system para-virtualization using a hypervisor that is implemented in a partition of the host system Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Computer system para-virtualization using a hypervisor that is implemented in a partition of the host system patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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